What does it mean that people are divided into three, six and nine grades?

Among the wood species, Huang Huali and mahogany are the best.

1, "three streams and nine streams" come from "three religions" and "nine religions" (including Confucianism, Taoism and Buddhism), while "nine religions" come from: Confucianism, Taoism, Buddhism, Ming, Mo, Yin and Yang, vertical and horizontal, miscellaneous studies and peasants (disorderly).

2. In the Jiupin Scale, it is divided into three grades: upper (upper intelligence), middle (middle person) and lower (lower stupidity). In each level, it is divided into: up, up, up, middle, down, down, up, down, middle and down.

3. The so-called rosewood Huang Huali is a literary name given by China literati. rosewood comes from the East and has a purple flavor. Generally speaking, ancient traditional furniture is divided into two categories, hardwood and cork.